In the past few years computers have become commonplace in commerce, in industry and in the home. As the amount of storage and computing capacity goes up, the more valuable are the computers, their component parts, the software stored on them and the information contained on disk, tape or optical storage devices. Smaller components have permitted the development of portable computers, e.g. laptops and notebooks. While original equipment manufacturers and software manufacturers have concentrated on developing password systems and other security devices to prevent unauthorized access to information on the computer, very little has been done to physically protect the computers themselves, apart from providing physical tethers. Even these are little deterrent to thieves, who are often equipped with cable cutters.
Protection is particularly difficult for laptop computers and the like, which are intended to be easily portable. The most vulnerable time for theft of laptop computers is when they are left on a user's desk or the like. When being transported, they are usually out of view, in a suitcase or car trunk, or are carried by hand, and therefore less likely to be stolen. Although large numbers of thefts of computers, laptops and components are reported to police and company security personnel, there is little chance of recovery.
It is costly to replace stolen computers. Perhaps more importantly though, considerable loss of time and resources occurs as a result of having to reconstitute lost information. This is particularly so for businesses, which rely heavily on computerized information and transactions. Also, all information stored in memory, e.g. on hard disk is also stolen, thus compromising security of information. Preventing theft of portable computers and the like is very important for businesses, and increasingly for business and other people who travel with portable computers. In high traffic area such as hospitals, and in poorly guarded areas (most small businesses) computers are easily targeted and stolen. Laptops left on a desk are particularly vulnerable.
Attempts have been made in the past to provide anti-theft devices for televisions, computers and the like. For example, U.S. Pat. No. 4,908,608 which issued Mar. 13, 1990 discloses electrical equipment with a security device which is controlled by a microprocessor. The microprocessor produces a warning from a warning device when the electrical power is lost and/or the equipment is moved. The device has an interface which requires a password and which also allows battery checks, alarm tests and alarm arming sequences to be passed between the equipment and the security device. The security device is mounted inside the computer, with the circuitry on a card installed in a so-called expansion slot in the computer. U.S. Pat. No. 5,317,304 which issued May 31, 1994 to A. Choi shows a battery-operated device which is used to trigger an alarm. The battery may be recharged. There may be an anti-tamper switch which senses when the device's housing is being removed. The alarm must be programmed for delay before triggering, and for loudness and duration. It has a disarming key. The device may be external to a computer or internal, mounted in an expansion slot. The device requires a key pad which is used to set various control parameters, such as alarm loudness, and provides a password protection and alarm disarming function. U.S. Pat. No. 4,686,514 which issued Aug. 11, 1987 discloses an electrically operated alarm which has a motion sensing switch, and an anti-tamper switch to detect opening of a computer case. None of the alarms are entirely satisfactory. The present invention is intended to provide an improved alarm, particularly for portable electrically operated devices.